6 BULLETIN 611, U. S. DEPARTMENT OF AGRICULTURE. 
so successful as in the control of those due to fungi ; until the efficacy 
of spraying may have become established, too much should not be 
expected from this method of control. 
A logical and seemingly practicable method of avoiding losses inci- 
dent to bacteriosis is in the possible development of immune or highly 
resistant varieties. Work along this line is now under way on the 
Pacific coast, but it is not known that any varieties altogether re- 
sistant to blight or even practically immune to it have thus far been 
brought to light. However, among the many thousands of seedling 
trees on the Pacific coast and the hundreds in the eastern United 
States, it would not seem too much to presume that for general 
orchard planting blight-resistant and otherwise desirable varieties 
will yet be found. Whenever such varieties are discovered, arrange- 
ments may be made with the Department of Agriculture for testing 
their susceptibility to this disease by means of inoculation experi- 
ments. Meanwhile, it is to be hoped that the planting of small com- 
mercial orchards and of trees for home use will be continued, as small 
groups of bearing trees over a wide range of territory will furnish 
valuable suggestions as to future commercial plantings. 
SUMMARY. 
Walnut blight, or bacteriosis, is distributed very generally through- 
out the eastern half of the country. Investigations by Mr. M. B. 
Waite and the writer have demonstrated its occurrence in Louisiana, 
the District of Columbia, Maryland, Delaware, Pennsylvania, and 
New York, and there seems to be no reason to suppose that it will 
not occur wherever Persian walnuts are grown in the United States. 
During the summer of 1916 pure cultures of the causal organism 
were obtained from naturally infected nuts ; inoculation experiments 
were conducted in healthy nuts and twigs, and these inoculations were 
uniformly successful in producing the disease. Cultural studies were 
conducted in the laboratory, and the results obtained corresponded 
with those reported by Pierce 1 and bv Smith. 2 
The writer's observations of this disease have covered one season 
only, and therefore definite conclusions as to its behavior under vary- 
ing seasonal conditions are not possible. It may be stated, however, 
that late infections were the rule during the season of 1916, and if 
this condition holds generally true from season to season it will con- 
stitute a striking difference between the behavior of the disease in the 
Middle Atlantic States and on the Pacific coast. 
Extensive experiments to control this disease by spraying have 
been conducted from time to time in California, but the results ob- 
tained have never been entirely satisfactory. Here, again, the diffei- 
1 Pierce, N. B. Op. cit. a Smith, B. E., Sniita, C. O., and Ramsey, H. J. Op. cit. 
